Cancer pain, particularly bone cancer pain, is a major symptom that significantly affects the quality of life of cancer patients. Clinical trials have demonstrated that acupuncture can alleviate cancer pain, but as yet evidence from basic scientific research is absent. An animal model of femur bone cancer pain, which mimics clinical cancer pain, has been established in our lab. We propose to use this model to evaluate the effects and mechanisms of electroacupuncture (EA) at acupoint G30 (Huan Tiao) on femoral cancer pain. The proposed hypotheses are: 1) EA of acupoint G30 at the optimal sets of parameters will significantly inhibit femur bone cancer-induced hyperalgesia. 2) Activity of the central neurons during cancer pain will be modulated by EA. The specific aims of this proposal are: Aim I: Evaluate the effects of EA on cancer-induced thermal hyperalgesia by measuring hindpaw withdrawal latency. Various combinations of frequencies (10 and 100 Hz) and stimulation durations (10, 15, 20 min) at the maximum tolerable electrical current of 1 mA will be administered to study the anti-hyperalgesic effects of EA in a mouse model of bone cancer pain. Aim II- Determine the optimal treatment protocol. With the optimal sets of parameters determined in Aim I, various EA treatment regimens will be conducted to establish how often treatments should be administered to achieve the greatest anti-hyperalgesic effects. Aim lll: Investigate the central mechanisms of action of EA on cancer pain. The modulation of EA on the activities of central neurons in the spinal cord will be investigated by characterizing Fos protein and dynorphin peptide expression with immunohistochemical staining. These studies will advance our knowledge of EA in control and management of cancer pain and provide useful information for designing future clinical trials using optimal EA parameters for patients with cancer pain. These studies will set a stage for further studying the mechanisms of EA in the control and management of cancer pain.